Fruits · Fruit
Star Fruit
Averrhoa carambola · also called Carambola, starfruit
Star fruit is a yellow-green, ribbed tropical fruit that makes a star shape when sliced. It is a source of vitamin C and fibre. If you have kidney disease, do not eat it or drink its juice: it has caused seizures and deaths in people with weak kidneys, and large amounts of sour juice have injured the kidneys of people without known kidney disease. No human trial shows that eating star fruit prevents or treats any illness.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Star Fruit
Star fruit is a mild, juicy fruit with some vitamin C and fibre. It is also the one common fruit that can poison people with kidney disease. It is a food, not a proven remedy.
What it is
Star fruit, also called carambola, is the fruit of Averrhoa carambola, a tropical tree in the wood sorrel family. It is yellow or greenish and makes a star shape when sliced. It is eaten fresh, in fruit salads, as a garnish or squeezed into juice.
USDA data for the raw fruit per 100 g: 31 kcal, 2.8 g fibre, 3.98 g sugars, 34.4 mg vitamin C, 133 mg potassium and 0.137 mg copper. One cup of slices (108 g) has about 34 kcal, 3.0 g fibre, 4.3 g sugars, 37 mg vitamin C and 144 mg potassium. It has no vitamin K. The USDA record gives no oxalate figure.
What the research shows
The firmest fact is about vitamin C: too little causes scurvy, and vitamin C foods prevent it. That is a nutrient fact, not a star fruit trial.
Reviews list blood sugar, cholesterol, blood pressure, antioxidant and anti-cancer effects, but these come from animal or lab work on leaf extracts, isolated compounds or juice. One review says reports of these effects have been done only in animals and in lab dishes, with a gap in clinical research and safety. We did not find a human trial of eating star fruit for any of them.
Where the fruit has been studied in people with kidney disease, the finding is harm.
Fruit versus extracts
The poisoning reports are for the fruit and its juice. The blood sugar, cancer and antioxidant findings are for leaf extracts, compounds or lab work. A result for one of these does not apply to another, and none of the laboratory results shows a benefit from eating a slice.
Amounts
This page gives no amounts to eat or drink. A review says the amount at which harm begins is not known. Ask your doctor, kidney team or dietitian what is right for you.
At a glance
Traditional uses history, not proof
- Eaten fresh, in fruit salads and as a garnish, and squeezed into juice
- Used in traditional medicine for diabetes, joint pain, cough and other complaints; long use is not proof it works, and it has caused poisoning
Studied for research
- Preventing scurvy through vitamin C, high certainty for the nutrient, no star fruit trial
- Use by people with kidney disease, against (documented harm)
- Blood sugar and diabetes, insufficient evidence (animal and lab work only)
- Antioxidant content, insufficient evidence (lab only)
- Cholesterol and blood pressure, insufficient evidence
- Cancer, insufficient evidence (leaf extract on cells in a dish)
Main compounds
- Vitamin C (ascorbic acid)
- Oxalate (oxalic acid)
- Caramboxin, the suspected nerve toxin
- Epicatechin, gallic acid forms and proanthocyanidins
Common forms
- Raw fruit, eaten whole including the skin (NKF; USDA values are for the raw fruit)
- Fresh or pickled juice (the poisoning reports involve large amounts of sour juice)
- Star fruit-infused liquor (one kidney injury report)
- Leaf and root extracts (used in animal and lab studies, not the same as the fruit)
Research links: National Kidney Foundation: Why You Should Avoid Eating Starfruit · Review of 126 published cases of star fruit poisoning (2017) · Narrative review of kidney and nerve toxicity (2021) · NHS: Scurvy · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Averrhoa carambola
- Naming authority
- L. (GBIF accepted; usageKey 2891641)
- Common names
- Star fruit (English); Starfruit (English); Carambola (English); Carambola (Spanish)
- Family or group
- Oxalidaceae (the wood sorrel family).
- Classification
- Plantae > Tracheophyta > Magnoliopsida > Oxalidales > Oxalidaceae > Averrhoa > Averrhoa carambola
- Native range
- A 2021 review says it is widely grown in southern China, Southeast Asia, India and northern South America. The NKF says it is a tropical fruit originally from Asia.
- Habitat
- Tropical regions (NKF).
- What it looks like
- Roots: Not verified.; Stems: Not verified.; Leaves: Not verified.; Flowers: Not verified.; Fruit: The fruit is yellow or greenish and star-shaped when sliced (NKF). USDA household portions: small 70 g, medium 91 g, large 124 g.
- Cultivation
- Not verified from a source read, beyond the regions above.
- Harvest and processing
- Eaten raw as fruit or squeezed into juice (2021 review). Commercial juice may be pickled and diluted (2001 case report). A star fruit-infused liquor is described in a 2026 case report.
- Look-alikes and adulterants
- Name: Bilimbi (Averrhoa bilimbi); Note: A related fruit. A 2017 case report links bilimbi to nerve toxicity in a dialysis patient; it is a different fruit and is not covered here.
- Sustainability and conservation
- Not assessed.
Photographs
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Traditional medicine | A 2021 review says star fruit has traditionally been used for diabetes and diabetic kidney disease, joint pain, vomiting, kidney stones, cough, hangovers and chronic paroxysmal headache. Long use is not proof it works, and the same review says bioactivity research has been done only in animals and lab dishes. | p34475822 |
| Kidney disease poisoning | Reports of poisoning in dialysis patients date to at least 2000 in this record. A 2013 chemistry paper reported the isolation of caramboxin as the likely toxin. | p10676715 |
Traditional use shows how it was used. It does not show that it works or is safe today.
What is inside, and how it may work
What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.
Main compounds
| Compound | Family | Where it is concentrated | Activity studied | Level of evidence |
|---|---|---|---|---|
| Ascorbic acid (vitamin C) PubChem 54670067 | vitamin | Fruit USDA: 34.4 mg per 100 g raw; 37.2 mg per cup of slices (108 g) | Essential nutrient. Identified in star fruit juice by lab analysis. Prevents scurvy when intake is too low. 30 32 28 18 | Human data |
| Oxalic acid and oxalate PubChem 971 | organic acid | Fruit and juice The USDA record has no oxalate figure; reviews call it high | Oxalate crystals injured the kidneys in case reports after large amounts of sour juice or fruit. 31 5 23 22 | Case report |
| Caramboxin | phenylalanine-like amino acid derivative (as described in the 2013 paper) | Fruit | Suspected nerve toxin. Authors say it blocks GABA binding and activates glutamate receptors, based on animal and lab work. 8 3 23 | Animal research |
| Epicatechin, gallic acid forms and proanthocyanidins | polyphenols | Juice and residue | Antioxidant activity in a test tube. No human trial of benefit was found. 18 | Laboratory research |
| Fibre and copper | nutrients | Fruit USDA per 100 g: 2.8 g fibre, 0.137 mg copper | Nutrient content only; no star fruit trial of these was found. 32 | Composition only |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Oxalate deposition in kidney tubules | Not applicable | Kidney biopsies in case reports show calcium oxalate crystals, tubular damage and interstitial inflammation. 5 9 1 22 | Human case report |
| GABA and glutamate systems (neurotoxicity) | GABA binding, glutamate receptors | A fruit fraction blocked GABA binding and caused seizures when injected into animal brains; caramboxin is reported to act on glutamate receptors. These findings are from animals and lab work. 3 8 23 | Animal research |
| Liver CYP enzyme inhibition | CYP3A and CYP1A2, 2A6, 2C8, 2C9, 2D6, 2E1 | Star fruit juice blocked these liver enzymes in human liver tissue in a test tube. No time-dependent inhibition was seen. 11 24 | Laboratory research |
| Antioxidant activity | Not applicable | Phenolic compounds show antioxidant activity in a test tube. 18 | Laboratory research |
Absorption, metabolism and elimination
- Absorption
- Not studied for star fruit.
- Distribution
- Not found.
- Metabolism
- Not found for the toxin.
- Elimination
- Healthy kidneys clear the toxin; diseased kidneys do not (NKF). Dialysis removes it in reported cases.
- Bioavailability
- Not established for vitamin C, oxalate or caramboxin from star fruit.
Isolated compounds versus whole extracts
Poisoning reports are for the fruit and its juice, sometimes pure sour juice or fruit-infused liquor. Lab and animal work used leaf extracts, a toxic fraction or compounds, and test-tube enzyme work used juice at 0.2 to 6% in a test tube. None of these equals a slice of fruit eaten by a person with healthy kidneys.
Nutritional composition
Nutrition from USDA FoodData Central (Carambola, (starfruit), raw, FDC 171715, SR Legacy, last updated 4/1/2019, read 2026-10-25). Per 100 g: 31 kcal, 91.4 g water, 1.04 g protein, 0.33 g fat, 6.73 g carbohydrate, 2.8 g fibre, 3.98 g total sugars, 3 mg calcium, 0.08 mg iron, 10 mg magnesium, 12 mg phosphorus, 133 mg potassium, 2 mg sodium, 0.12 mg zinc, 0.137 mg copper, 34.4 mg vitamin C, 0.017 mg vitamin B6, 12 micrograms folate (DFE), 3 micrograms vitamin A (RAE), 66 micrograms lutein plus zeaxanthin, and no vitamin K. One cup of slices (108 g): about 33.5 kcal, 3.0 g fibre, 4.3 g sugars, 37.2 mg vitamin C, 143.6 mg potassium and 0.15 mg copper. One medium fruit (91 g): about 28 kcal, 2.5 g fibre, 31 mg vitamin C and 121 mg potassium. Figures vary with variety and ripeness. The USDA record has no oxalate figure. It is mainly a vitamin C and fibre food. No dried or canned figures were read.
1 high certainty4 not enough evidence1 evidence against
What was looked at
The 6 benefits and uses checked for Star Fruit, each with how strong the evidence is. Tap one to open it.
- Preventing vitamin C shortage (scurvy)High certainty
- Blood sugar and diabetesNot enough evidence
- Antioxidant compoundsNot enough evidence
- Eating star fruit when you have kidney diseaseEvidence against
- Cholesterol and blood pressureNot enough evidence
- Cancer (cells in a dish)Not enough evidence
Lab markers tracked in the studies
Blood glucoseBlood fats (LDL, HDL, triglycerides)
What is Star Fruit good for?
The main studied uses and how strong the human evidence is for each. Almost all of the benefit claims come from animal or lab work, and the human research is mostly about harm.
Benefits, one by one
Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.
Preventing vitamin C shortage (scurvy)
High certaintyScurvy comes from too little vitamin C over a long time. Star fruit is one fruit that supplies vitamin C: USDA lists 34.4 mg per 100 g. No trial tested star fruit itself for scurvy.
3 studiesRaw fruit as food. Cooking and storage can change vitamin C; star fru…
Studies, doses and limits
What the trials found
The NHS says scurvy is caused by not having enough vitamin C in the diet over a long period, that vitamin C is mainly found in fruit and vegetables, and that adults aged 19 to 64 need 40 mg a day. USDA lists 34.4 mg of vitamin C per 100 g raw star fruit, which is 37.2 mg in one cup of slices (108 g).
Results
The general link between vitamin C foods and scurvy is well accepted. No trial of star fruit was found. For people with kidney disease, star fruit is not a safe way to get vitamin C (see the Safety tab).
Effect sizes as reported
USDA: 34.4 mg vitamin C per 100 g; 37.2 mg per cup of slices (108 g). NHS: 40 mg a day for adults 19 to 64.
Why this rating
High for the general point that a diet with enough vitamin C prevents scurvy (health-agency statements). There is no star fruit trial, and a normal varied diet already prevents scurvy.
Form and dose studied
Raw fruit as food. Cooking and storage can change vitamin C; star fruit juice and dried fruit were not researched.
Who was studied
People with very limited diets are the group at risk of scurvy (NHS).
Limits
Not a trial of star fruit. Many other fruits supply vitamin C without the kidney danger of star fruit.
Why researchers looked
Star fruit is often described as a vitamin C fruit, so people ask whether it helps prevent a shortage.
Traditional use
Star fruit is eaten fresh, in juice and as a traditional remedy in some places; long use is not proof it works.
Proposed mechanism Authoritative guidance
Vitamin C (ascorbic acid) is needed by the body; the NHS says it is found mainly in fruit and vegetables. Star fruit is one source among many.
A proposed mechanism does not show that the effect happens in people.
Anyone with bleeding gums, easy bruising, tiredness and joint pain should see a doctor. People with kidney disease should not use star fruit as a vitamin C source.
Blood sugar and diabetes
Not enough evidenceStar fruit is described as a traditional remedy for diabetes. Reviews describe lowered blood sugar from leaf extracts and isolated compounds in animals and lab tests, but no human trial of eating the fruit was found.
3 studiesLeaf extracts, isolated compounds and fruit were all described in the…
Studies, doses and limits
What the trials found
A 2021 review (Lakmal) lists reported blood sugar lowering effects and a 2021 review (Luan) says the bioactivity reports were made only in animals and lab dishes, with a gap in clinical research. No human trial of star fruit for blood sugar was found.
Results
No human result. Two diabetic adults who ate star fruit as a diabetes remedy developed biopsy-proven oxalate kidney injury instead (case reports, see Safety tab).
Why this rating
Insufficient: the evidence is from animal and lab work on leaf extracts and isolated compounds. Case reports in people show harm, not benefit.
Form and dose studied
Leaf extracts, isolated compounds and fruit were all described in the reviews; they are not the same as a slice of fruit.
Who was studied
People with diabetes are among those who use star fruit as a remedy, and they are among those with the reported kidney injuries.
Limits
No human trial. The review abstracts do not give numbers for the animal results.
Why researchers looked
A 2021 review lists diabetes among the traditional uses of star fruit, so researchers tested it.
Traditional use
Star fruit is eaten fresh, in juice and as a traditional remedy in some places; long use is not proof it works.
Proposed mechanism Laboratory research
A review proposes that fibre and a compound called 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione may lower blood sugar. These are proposed mechanisms from lab and animal work.
A proposed mechanism does not show that the effect happens in people.
Do not use star fruit, its leaf or its root as a diabetes remedy. Two diabetic adults who did so had kidney injury.
Antioxidant compounds
Not enough evidenceLab analysis found vitamin C, epicatechin, gallic acid forms and proanthocyanidins in star fruit. These show antioxidant activity in a test tube. No trial shows that eating the fruit gives a health benefit from them.
2 studiesJuice and residue extracts were analysed in the lab.
Studies, doses and limits
What the trials found
A 2004 lab study (Shui and Leong) attributed the main antioxidant activity of star fruit juice and residue extracts to phenolic compounds, identifying L-ascorbic acid, (-)epicatechin and gallic acid in gallotannin forms, and proanthocyanidins.
Results
A description of what is in the fruit. No human result.
Effect sizes as reported
No numbers in the abstract.
Why this rating
Insufficient: a test-tube finding with no human outcome.
Form and dose studied
Juice and residue extracts were analysed in the lab.
Limits
A lab chemistry paper from 2004; it does not show that eating star fruit changes antioxidant status in people.
Why researchers looked
Plant pigments are often marketed as antioxidants, so people ask whether star fruit has them.
Traditional use
Star fruit is eaten fresh, in juice and as a traditional remedy in some places; long use is not proof it works.
Proposed mechanism Laboratory research
Phenolic compounds scavenge free radicals in a test tube. That is a lab measurement, not a proven effect in the body.
A proposed mechanism does not show that the effect happens in people.
None specific.
Eating star fruit when you have kidney disease
Evidence againstThere is no good evidence of benefit, and many case reports of serious harm. The National Kidney Foundation says people with kidney disease should avoid star fruit.
3 studiesFruit and juice.
Studies, doses and limits
What the trials found
Case series of dialysis and kidney-failure patients report hiccups, confusion, seizures and death. In one series, 8 of 20 patients died. A review of 126 published patients found no deaths among those with normal kidneys, 36% with chronic kidney insufficiency and 27% on dialysis (24% overall).
Results
Harm, not benefit. See the Safety tab for details and for who is at risk.
Effect sizes as reported
8 of 20 died (Chang 2000); overall mortality 24% in 126 reported patients (Chua 2017).
Why this rating
Against: no benefit is shown and harm is documented in case series. Reports come from written-up cases, so the real chance of harm for any person is not known.
Form and dose studied
Fruit and juice.
Who was studied
People with chronic kidney disease, on dialysis or with weak kidneys.
Limits
Case reports cannot give how often harm happens.
Why researchers looked
Most of the human research on star fruit is about poisoning, because doctors have reported many cases in people with weak kidneys.
Traditional use
Star fruit is eaten fresh, in juice and as a traditional remedy in some places; long use is not proof it works.
Proposed mechanism Case report
Oxalate can damage the kidneys, and a nerve toxin called caramboxin is cleared by healthy kidneys but not by diseased ones. The nerve mechanism is from animal and lab work.
A proposed mechanism does not show that the effect happens in people.
People with kidney disease should avoid star fruit and its juice.
Cholesterol and blood pressure
Not enough evidenceReviews list lowering of cholesterol and blood pressure among reported effects of star fruit. A 2025 review of eight fruits, star fruit among them, gives no star fruit result in its abstract. No human trial of eating the fruit was found.
2 studiesFruit, leaf and parts were mixed in the reviews.
Studies, doses and limits
What the trials found
The 2021 Lakmal review lists hypocholesterolemic (fibre) and hypotensive (apigenin) effects among reported benefits. The 2025 Flores review covers rat and human studies on eight fruits including star fruit, but the abstract gives no star fruit result.
Results
No human result for star fruit.
Why this rating
Insufficient: reviews report these effects without human trial results in the abstracts we read.
Form and dose studied
Fruit, leaf and parts were mixed in the reviews.
Limits
Only review abstracts were read; the full text may contain more.
Why researchers looked
Fruit fibre and plant compounds are often credited with helping blood fats and blood pressure.
Traditional use
Star fruit is eaten fresh, in juice and as a traditional remedy in some places; long use is not proof it works.
Proposed mechanism Laboratory research
A review proposes a fibre effect on cholesterol and an effect of the plant compound apigenin on blood pressure. These are proposed, not shown in people.
A proposed mechanism does not show that the effect happens in people.
None specific.
Cancer (cells in a dish)
Not enough evidenceA leaf extract reduced the survival of breast cancer cells in a dish. This is lab work on a leaf extract, not the fruit, and tells us nothing yet about people.
2 studiesEthanol extract of leaf, not a food.
Studies, doses and limits
What the trials found
A 2024 study tested an ethanol extract of star fruit leaf on MDA-MB-231 triple-negative breast cancer cells. Cell viability fell with higher concentration (IC50 20.89 micrograms per mL at 48 hours).
Results
Lab result only; no animal or human result in this study.
Effect sizes as reported
IC50 20.89 micrograms per mL at 48 hours.
Why this rating
Insufficient (lab only): cells in a dish and a leaf extract, not the fruit.
Form and dose studied
Ethanol extract of leaf, not a food.
Limits
Cell-line work. Not evidence about eating the fruit.
Why researchers looked
Researchers screen plant extracts against cancer cells to find leads.
Traditional use
Star fruit is eaten fresh, in juice and as a traditional remedy in some places; long use is not proof it works.
Proposed mechanism Laboratory research
The extract contains flavonoids, saponins and steroids according to the authors, and lowered cell survival, colony growth and migration in lab tests.
A proposed mechanism does not show that the effect happens in people.
None specific.
Connections to the rest of health
How Star Fruit connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.
Explore every connection: goals, body systems, organs, symptoms, genes
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Nervous system | Adverse effect or risk | Documented risk | Hiccups, numbness, weakness and seizures follow star fruit in people with kidney disease. The mechanism evidence is from animals and lab work. Preparation or compound: Star fruit (caramboxin) |
14 3 8 |
| Immune System | Biological association | High certainty | Studied for: Preventing vitamin C shortage (scurvy) Studied for: Antioxidant compounds | 27 28 32 18 12 2 13 |
| Endocrine System | Biological association | Not enough evidence | Studied for: Blood sugar and diabetes | 12 13 1 |
| Urinary System | Biological association | Evidence against | Studied for: Eating star fruit when you have kidney disease | 29 4 6 |
| Nervous System | Biological association | Evidence against | Studied for: Eating star fruit when you have kidney disease | 29 4 6 |
| Cardiovascular System | Biological association | Not enough evidence | Studied for: Cholesterol and blood pressure | 12 7 |
C. Body parts and organs
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Kidneys | Adverse effect or risk | Documented risk | Oxalate can injure kidneys, and people with kidney disease cannot clear the toxin. People with kidney disease should avoid star fruit; large amounts of sour juice have injured kidneys in case reports. Preparation or compound: Star fruit or juice (oxalate and caramboxin) |
29 5 1 23 |
| Brain | Adverse effect or risk | Documented risk | Confusion, coma and seizures including status epilepticus are reported in people with kidney failure. Preparation or compound: Star fruit (caramboxin) |
19 10 23 |
E. Health conditions
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Blood glucose | Biological association | Not enough evidence | Measured in trials: no human data. A lab change is not the same as a health benefit. | 13 1 |
| Blood fats (LDL, HDL, triglycerides) | Biological association | Not enough evidence | Measured in trials: no human data. A lab change is not the same as a health benefit. | 7 12 |
J. Genes, receptors and enzymes
K. Biological pathways
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Ascorbic acid (vitamin C) | Biological association | Human | Essential nutrient. Identified in star fruit juice by lab analysis. Prevents scurvy when intake is too low. Preparation or compound: Fruit |
30 32 28 18 |
| Oxalic acid and oxalate | Biological association | Case report | Oxalate crystals injured the kidneys in case reports after large amounts of sour juice or fruit. Preparation or compound: Fruit and juice |
31 5 23 22 |
| Caramboxin | Biological association | Animal | Suspected nerve toxin. Authors say it blocks GABA binding and activates glutamate receptors, based on animal and lab work. Preparation or compound: Fruit |
8 3 23 |
| Epicatechin, gallic acid forms and proanthocyanidins | Biological association | In vitro | Antioxidant activity in a test tube. No human trial of benefit was found. Preparation or compound: Juice and residue |
18 |
| Fibre and copper | Biological association | Composition only | Nutrient content only; no star fruit trial of these was found. Preparation or compound: Fruit |
32 |
Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).
Evidence at a glance: what the research found for 6 outcomes
Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.
The evidence
The research centre for Star Fruit. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).
How we rate evidence
High certainty
Several well-run trials or reviews agree; further research is unlikely to change the picture much.
Moderate certainty
Good trials point the same way, but some doubt remains.
Low certainty
Small, short or inconsistent trials. The finding could change with better research.
Very low certainty
Very little or very weak human data. Treat as a possibility only.
Mixed findings
Trials or reviews disagree with each other.
Not enough evidence
Not enough human research to say either way.
Evidence against
Good research found no benefit, or found harm.
We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing star fruit summary, re-checked nutrition at USDA FoodData Central, and searched PubMed for human reports, reviews, mechanism and enzyme studies. Only abstracts were read for studies; two allergy reports were read by title only. Items we could not verify are flagged in the research gaps.
Study library: every study we checked 32
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Abeysekera 2015 Star fruit toxicity: a cause of both acute kidney injury and chronic kidney disease: a report of two cases. BMC Res Notes · PMID 26680759 · DOI |
Case report |
2 Two diabetic adults (a 56-year-old woman with normal kidney function and a 60-year-old man) who ate star fruit as a remedy for diabetes |
Star fruit juice or fruit Fruit A large amount at once (woman); many fruits in a short time on top of regular use for 2 to 3 years (man) |
Both had biopsy-proven oxalate kidney injury. The woman had sudden kidney injury after a large amount of juice. The man had acute-on-chronic kidney failure. Both recovered over about 2 weeks without dialysis. Neither had diabetic kidney damage on biopsy. The authors believe the man's case is the first reported chronic kidney disease from long, heavy star fruit eating. Both recovered within about 2 weeks Methods, limits and fundingOutcomes: Kidney injury and biopsy findings Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Beas-Guzman 2024 Ethanolic Extract of Averrhoa carambola Leaf Has an Anticancer Activity on Triple-Negative Breast Cancer Cells: An In Vitro Study. Pharmaceutics · PMID 39861654 · DOI |
Laboratory research in-vitro |
MDA-MB-231 human breast cancer cells in a dish | Ethanol extract of star fruit leaf Leaf (not the fruit) Concentrations in micrograms per mL (lab detail) 48 hours · vs Untreated cells |
Cell viability fell with concentration (IC50 20.89 micrograms per mL at 48 hours). At 15 micrograms per mL only 2.63% of cells formed colonies. Migration was reduced. Lower concentrations plus doxorubicin had an additive effect. IC50 20.89 micrograms per mL Methods, limits and fundingOutcomes: Cell viability, colony growth, migration, with doxorubicin Limitations: Cells in a dish, a leaf extract, not the fruit. No animal or human result. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Carolino 2005 Convulsant activity and neurochemical alterations induced by a fraction obtained from fruit Averrhoa carambola. Neurochem Int · PMID 15843046 · DOI |
Animal research animal |
Animals given a fraction of star fruit into the brain cortex; lab binding tests | A neurotoxic fraction from star fruit (AcTx) Fruit |
The fraction blocked GABA binding in a concentration-dependent way (IC50 0.89 micromolar). After direct injection into the cortex, animals had tonic-clonic seizures that became status epilepticus. The fraction was a small non-protein molecule different from oxalic acid. IC50 0.89 micromolar for GABA binding Methods, limits and fundingOutcomes: Seizures, GABA and glutamate systems Limitations: Animals, injected into the brain, so not like eating the fruit. Funding and conflicts: Research support from non-US government sources is listed; no industry funding is stated. Read: abstract |
| Chang 2000 Fatal outcome after ingestion of star fruit (Averrhoa carambola) in uremic patients. Am J Kidney Dis · PMID 10676715 · DOI |
Case series |
20 20 patients with kidney failure who became ill after eating star fruit or its juice, treated over 10 years at one hospital |
Star fruit or star fruit juice Fruit |
Symptoms were sudden limb numbness, muscle weakness, intractable hiccups, drowsiness or confusion and seizures. Eight patients died, including one who had not yet started dialysis; death came within 5 days despite emergency hemodialysis. Survivors improved with supportive care and recovered without obvious lasting problems. 8 of 20 died Methods, limits and fundingOutcomes: Symptoms and outcome Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Chen 2001 Acute oxalate nephropathy after ingestion of star fruit. Am J Kidney Dis · PMID 11157385 · DOI |
Case report |
2 2 patients who drank large amounts of sour star fruit juice |
Pure sour carambola juice (fresh or mildly diluted pickled juice) Fruit juice Large quantities (not measured in the abstract) |
Both patients developed nausea, vomiting, abdominal pain and backache within hours, then sudden kidney failure that needed dialysis. Biopsies showed oxalate kidney damage. Kidney function recovered after 4 weeks. The authors say commercial carambola juice is usually pickled and diluted, which lowers its oxalate a lot. They advise against large amounts of pure sour juice, especially on an empty stomach or when dehydrated. 2 of 2 recovered kidney function at 4 weeks Methods, limits and fundingOutcomes: Kidney injury Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Chua 2017 Association of renal function and symptoms with mortality in star fruit (Averrhoa carambola) intoxication. Clin Toxicol (Phila) · PMID 28443386 · DOI |
Systematic review |
126 126 patients from 33 published reports (1993 to 2016); mean age 54.4 |
Star fruit Fruit Reported amounts varied |
The most common symptom was hiccups (65%). Confusion and seizures were the symptoms linked to death (42% and 61%). No patient with normal kidney function died. Mortality was 36% with chronic kidney insufficiency and 27% for those on dialysis, 24% overall. Patients with normal kidney function had eaten more fruit than those with impaired kidneys. Hemodialysis was the most common treatment (59%), and early, continuous dialysis seemed to help. Overall mortality 24%; 0% with normal kidneys Methods, limits and fundingOutcomes: Symptoms, kidney function and death Limitations: These are published case reports, so they over-represent severe cases and cannot give the real risk for a person who eats a slice. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Flores Flores 2025 Potential of Fruits to Improve Dyslipidemias: A Pilot Review. Vasc Health Risk Manag · PMID 40322293 · DOI |
Narrative review mixed |
Eight fruits (pomegranate, star fruit, Rosa roxburghii, pineapple, tree tomato, coffee, apple, passion fruit), research in rats and humans | Various fruits and parts Root, leaf, stem, peel and pulp |
The abstract says the review summarises rat and human research on eight fruits, star fruit among them, for dyslipidemia and related effects. It gives no result for star fruit. None given for star fruit in the abstract Methods, limits and fundingOutcomes: Blood fats and related health effects Limitations: A pilot narrative review. The abstract has no star fruit result, and the full text was not read. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Garcia-Cairasco 2013 Elucidating the neurotoxicity of the star fruit. Angew Chem Int Ed Engl · PMID 24281890 · DOI |
Laboratory research mixed |
Chemical isolation work with tests in living animals and in lab preparations | Compound isolated from star fruit Fruit |
The group isolated caramboxin, a phenylalanine-like molecule they say is responsible for the poisoning. Tests in animals and in lab preparations point to actions on glutamate receptors, which explain its convulsant and nerve-damaging effects. No numbers in the abstract Methods, limits and fundingOutcomes: Identity and action of the toxin Limitations: Animal and lab work. The abstract is a short summary of a chemistry paper. Funding and conflicts: Research support from non-US government sources is listed; no industry funding is stated. Read: abstract |
| Herath 2021 Acute Kidney Injury Following Star Fruit Ingestion: A Case Series. Wilderness Environ Med · PMID 33518496 · DOI |
Case series |
4 4 men aged 28 to 55 in Sri Lanka who developed sudden kidney injury after eating star fruit |
Star fruit Fruit Amounts were traced but are not given in the abstract |
Patients had nausea, vomiting, abdominal and back pain, then low urine output and rising creatinine. All had oxalate crystals in the urine, and kidney biopsies showed tubular damage with calcium oxalate crystals. Two needed intermittent hemodialysis for about a week. Kidney function was back to normal within a month in all four. 4 of 4 recovered by one month Methods, limits and fundingOutcomes: Kidney injury, urine and biopsy findings Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Herbland 2009 Star fruit poisoning is potentially life-threatening in patients with moderate chronic renal failure. Intensive Care Med · PMID 19360394 · DOI |
Case series |
6 6 patients with moderate chronic kidney failure admitted to intensive care |
Star fruit Fruit |
All six had sudden kidney failure and needed a breathing tube because of coma. Common symptoms were hiccups, confusion, seizures and coma; three had status epilepticus. Four survived without lasting problems and two died. The authors say severe poisoning can occur even with moderate kidney failure. 2 of 6 died Methods, limits and fundingOutcomes: Symptoms and outcome Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Hidaka 2004 Potent inhibition by star fruit of human cytochrome P450 3A (CYP3A) activity. Drug Metab Dispos · PMID 15155547 · DOI |
Laboratory research in-vitro |
Human liver microsomes (lab preparation) with juices of eight tropical fruits, grapefruit and Valencia orange | Star fruit juice Fruit juice 0.2 to 6.0% juice by volume in the test tube Test tube · vs Grapefruit and Valencia orange juice |
Star fruit juice was the strongest inhibitor of the eight tropical fruits. At 5.0% juice, activity fell to 0.1% of normal, versus 14.7% with grapefruit. Longer pre-incubation did not change the effect, so the authors think there is no mechanism-based inhibitor. Residual activity 0.1% (star fruit) vs 14.7% (grapefruit) at 5% juice Methods, limits and fundingOutcomes: Activity of CYP3A, a liver enzyme that processes many medicines (midazolam test) Limitations: A test-tube result with liver tissue. It does not show what happens to a medicine in a person who eats the fruit. Funding and conflicts: Research support from non-US government sources is listed; no industry funding is stated. Read: abstract |
| Lakmal 2021 Nutritional and medicinal properties of Star fruit (Averrhoa carambola): A review. Food Sci Nutr · PMID 33747490 · DOI |
Narrative review mixed |
Published reports on star fruit benefits and toxicity | Star fruit (fruit, leaf and compounds) Fruit and others |
The authors list reported antioxidant, blood sugar lowering, blood pressure lowering, cholesterol lowering, anti-inflammatory, anti-infective, antitumour and immune effects, and name possible mechanisms. They also list who is at risk of toxicity: chronic kidney disease, gut disease, chronic pancreatitis, dehydration, eating on an empty stomach and a high oxalate content. They say the amount at which benefit turns into harm is still not known. No numbers in the abstract Methods, limits and fundingOutcomes: Reported benefits, mechanisms, and what raises poisoning risk Limitations: A narrative review, not a trial. The abstract does not say how many human studies were found. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Luan 2021 Traditional Uses, Phytochemical Constituents and Pharmacological Properties of Averrhoa carambola L.: A Review. Front Pharmacol · PMID 34475822 · DOI |
Narrative review mixed |
Published reports on star fruit botany, chemistry, pharmacology and toxicity | Star fruit (fruit, leaf, root, extracts) Mixed |
The review lists about 132 compounds and says traditional uses include diabetes, diabetic kidney disease, joint pain, vomiting, cough and hangover. It says reports of the bioactivities have been done only in animals and in lab dishes, and that there is a gap in research on clinical settings and safety. About 132 compounds isolated Methods, limits and fundingOutcomes: Traditional uses, compounds, bioactivities, toxicity Limitations: A narrative review. Written to support product development; the abstract is promotional about the fruit's potential. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Neto 2003 Intoxication by star fruit (Averrhoa carambola) in 32 uraemic patients: treatment and outcome. Nephrol Dial Transplant · PMID 12480969 · DOI |
Case series |
32 32 patients with kidney failure (20 on hemodialysis, 8 on peritoneal dialysis, 4 not yet on dialysis) |
Star fruit Fruit |
Persistent hiccups occurred in 30 patients (93.75%), vomiting in 22 (68.7%), confusion or agitation in 21 (65.6%), weakness, numbness or insomnia in 13 (40.6%) and seizures in 7 (21.8%). Patients treated promptly with hemodialysis recovered without lasting problems. Severe cases who were untreated or treated with peritoneal dialysis did not survive. Hiccups 93.75%; seizures 21.8% Methods, limits and fundingOutcomes: Symptoms, treatment and outcome Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Some patients were followed from a distance after referral. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Numata 2015 A case of oral allergy syndrome due to star fruit sensitized from atopic hands. Allergol Int · PMID 26433542 · DOI |
Case report |
1 One person (title only; no abstract in PubMed) |
Star fruit Fruit |
Only the title was read: it reports oral allergy syndrome (itchy mouth reaction) to star fruit, with sensitisation said to come from eczema-affected hands. 1 case Methods, limits and fundingOutcomes: Allergic reaction Limitations: Title only; no abstract text was available, so details are not given. Funding and conflicts: Not stated Read: title-only |
| Raciti 2023 Death associated with ingestion of starfruit (Averrhoa carambola) in a patient with chronic kidney disease. Am J Emerg Med · PMID 37394384 · DOI |
Case report |
1 A 74-year-old woman with chronic kidney disease and diabetes |
Two whole star fruit Fruit Two whole fruit |
She came to the emergency department with intractable hiccups after eating two whole star fruit and became critically ill. She had several rounds of hemodialysis and died in hospital. The authors call it the first reported death from star fruit in the US. 1 death Methods, limits and fundingOutcomes: Outcome Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Shan 2026 Case Report: A case of acute kidney injury due to star fruit-infused liquor. Front Med (Lausanne) · PMID 42712500 · DOI |
Case report |
1 One patient who drank large quantities of star fruit-infused liquor |
Star fruit steeped in alcohol Fruit Large quantities (not measured in the abstract) |
Biopsy confirmed oxalate nephropathy from star fruit. Kidney function improved with treatment, but long-term follow-up showed progression to chronic kidney disease. 1 case, progressed to chronic kidney disease Methods, limits and fundingOutcomes: Kidney injury Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Shui 2004 Analysis of polyphenolic antioxidants in star fruit using liquid chromatography and mass spectrometry. J Chromatogr A · PMID 14753772 · DOI |
Laboratory research in-vitro |
Star fruit juice and residue extracts analysed in the lab | Star fruit juice and residue extract Fruit Lab analysis |
The main antioxidants were attributed to phenolic compounds. Peaks were identified as L-ascorbic acid, epicatechin and gallic acid in gallotannin forms. Other major antioxidants were attributed to proanthocyanidins (dimers to pentamers of catechin or epicatechin). No numbers in the abstract Methods, limits and fundingOutcomes: Which compounds give antioxidant activity in a test tube Limitations: Lab chemistry; test-tube antioxidant activity is not a health effect in people. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Tsai 2005 Status epilepticus induced by star fruit intoxication in patients with chronic renal disease. Seizure · PMID 16169255 · DOI |
Case series |
53 2 new patients with chronic kidney failure before dialysis, plus 51 cases from the literature |
Star fruit Fruit |
Among 53 patients, 16 had seizures (30%). The death rate was 75% in those with seizures. The authors found a poor link between how weak the kidneys were and the chance of dying, and advise people with chronic kidney disease to avoid star fruit, especially the elderly. 16 of 53 had seizures; 75% mortality in the seizure group Methods, limits and fundingOutcomes: Seizures and death Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. The abstract gives a very low death rate for patients without seizures that is not repeated here because it looks like a typing error. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Tse 2003 Star fruit intoxication in uraemic patients: case series and review of the literature. Intern Med J · PMID 12823678 · DOI |
Case series |
7 7 dialysis patients in two Hong Kong centres |
Star fruit Fruit |
Hiccups, confusion, vomiting, impaired consciousness, muscle twitching and high potassium (hyperkalaemia) appeared soon after eating star fruit. Most patients recovered after intensified dialysis or on their own, and no one died. The authors recommend that uraemic patients avoid star fruit completely. 0 of 7 died Methods, limits and fundingOutcomes: Symptoms and outcome Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Vazquez-Revuelta 2021 Anaphylactic shock after first exposure to star fruit in a bird keeper. Ann Allergy Asthma Immunol · PMID 33450399 · DOI |
Case report |
1 One person who kept birds (title only; no abstract in PubMed) |
Star fruit Fruit |
Only the title was read: it reports anaphylactic shock after a first exposure to star fruit in a bird keeper. 1 case Methods, limits and fundingOutcomes: Allergic reaction Limitations: Title only; no abstract text was available, so details are not given. Funding and conflicts: Not stated Read: title-only |
| Yasawardene 2020 Mechanisms of star fruit (Averrhoa carambola) toxicity: A mini-review. Toxicon · PMID 32966829 · DOI |
Narrative review mixed |
Published mechanism research on star fruit toxicity | Star fruit Fruit |
The fruit contains oxalic acid and caramboxin. The kidney harm is due to oxalate deposits in the kidney tubules, causing acute tubular necrosis and interstitial nephritis. The authors say caramboxin activates excitatory receptors and inhibits GABA receptors in the brain, which would explain confusion, seizures and status epilepticus, and that uraemic encephalopathy may also play a part. No numbers in the abstract Methods, limits and fundingOutcomes: Mechanisms Limitations: A mini-review; mechanisms are proposed, not proven in people. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Yasawardene 2021 Nephrotoxicity and neurotoxicity following star fruit (Averrhoa carambola) ingestion: a narrative review. Trans R Soc Trop Med Hyg · PMID 33693950 · DOI |
Narrative review mixed |
136 10 case series and 28 case reports (136 people) plus 8 animal studies |
Star fruit Fruit |
Of 136 people, 94 (69.1%) had kidney impairment before eating the fruit, so about 3 in 10 did not. Kidney biopsies showed acute oxalate nephropathy. Nerve effects ranged from hiccups to status epilepticus. Oxalate and caramboxin are considered the main causes. The authors say caramboxin inhibits GABA binding and activates glutamate receptors, and that hemodialysis improved outcomes in neurotoxicity. 94 of 136 (69.1%) had prior kidney impairment Methods, limits and fundingOutcomes: Kidney and nerve effects, mechanisms Limitations: Case reports and case series show that harm can happen, not how often. Only cases that doctors wrote up are included. The mechanism part comes from animal work. Funding and conflicts: Funding and conflicts are not stated in the abstract. Read: abstract |
| Zhang 2007 Inhibition of human liver cytochrome P450 by star fruit juice. J Pharm Pharm Sci · PMID 18261370 · DOI |
Laboratory research in-vitro |
Human liver microsomes with star fruit juice | Star fruit juice Fruit juice 0.5 to 5% juice by volume in the test tube Test tube · vs No juice |
At 5.0% juice, all seven CYP enzymes tested were inhibited by more than 70%. The strongest effect was on CYP2A6 and the weakest on CYP3A4. No time-dependent inhibition was seen. More than 70% inhibition of all seven at 5% juice Methods, limits and fundingOutcomes: Activity of seven CYP liver enzymes Limitations: A test-tube result. No study of medicines in people was found. Funding and conflicts: Research support from non-US government sources is listed; no industry funding is stated. Read: abstract |
| s-fda-produce FDA: Selecting and Serving Produce Safely · Source |
Regulator n/a |
Methods, limits and fundingRead: full-text | ||
| s-gbif-averrhoa-carambola GBIF Backbone: Averrhoa carambola L. (usageKey 2891641) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-nhs-scurvy NHS: Scurvy · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-nhs-vitc NHS: Vitamin C · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-nkf-starfruit National Kidney Foundation: Why You Should Avoid Eating Starfruit · Source |
Regulator n/a |
Methods, limits and fundingRead: full-text | ||
| s-pubchem-ascorbic-acid PubChem: L-Ascorbic acid (CID 54670067) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-pubchem-oxalic-acid PubChem: Oxalic acid (CID 971) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-usda-fdc-171715 USDA FoodData Central: Carambola, (starfruit), raw (FDC 171715) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text |
What we do not know yet
- No human trial of eating star fruit for blood sugar, blood pressure, cholesterol or any other health outcome was found.
- The amount at which harm begins and how often people are harmed are not known; the poisoning reports are written-up cases.
- No study shows an effect of star fruit on medicines in people; the enzyme data are test-tube results.
- Allergy reports could only be read by title.
- Pregnancy, breastfeeding, children, pesticide residues and heavy metals were not researched, and the oxalate and caramboxin content of the fruit were not found in a source read.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue before the page changes.
Lab markers
What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".
Metabolic 1
Blood glucose
No human data in trials
The amount of sugar in the blood.
Not enough evidenceResults and what it means
Why it was measured
It is the main marker for diabetes and blood sugar control.
Statistical vs. clinical meaning
A lab or animal blood sugar change is not shown in people.
Safety implication
Two diabetic adults who used star fruit as a remedy had kidney injury.
| Study | Result | People | Product |
|---|---|---|---|
| 13 | Reported to fall with extracts and compounds in animals and lab tests; no human trial of the fruit | Animals and lab dishes (per the review) | Extracts and isolated compounds |
Other 1
Blood fats (LDL, HDL, triglycerides)
No human data in trials
Measures of cholesterol and other fats in the blood.
Not enough evidenceResults and what it means
Why it was measured
High LDL cholesterol and triglycerides are heart disease risk markers.
Statistical vs. clinical meaning
Nothing about star fruit can be concluded from the abstract.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 7 | No star fruit result given in the abstract | Rat and human studies of eight fruits (review) | Various fruit parts |
Safety
What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.
Main points to know 4
- If you have kidney disease, do not eat star fruit or drink its juice. The National Kidney Foundation says people with kidney disease should avoid star fruit because it contains a neurotoxin that healthy kidneys clear but diseased kidneys cannot. Case series report hiccups, confusion, seizures and deaths in people with kidney failure. In one series 8 of 20 died. A review of 126 published patients found 36% mortality with chronic kidney insufficiency and 27% for those on dialysis. These are written-up cases, so the real chance for any one person is not known. Case report 29 4 14 19 20 10 6 16
- People with normal kidneys have also been harmed, mostly after a lot of sour juice or many fruits. Oxalate in the fruit can injure the kidneys. Case reports describe sudden kidney injury within hours of drinking large amounts of pure sour juice, many fruits eaten at once, and star fruit-infused liquor. Biopsies showed oxalate crystals. Most recovered in weeks, but one report describes progression to chronic kidney disease. In a review of 136 reported people, about 3 in 10 had no known kidney impairment before. Case report 5 1 9 17 23
- Lab tests suggest star fruit juice may interfere with medicines, but this is untested in people. In human liver tissue in a test tube, star fruit juice blocked the liver enzyme CYP3A more than grapefruit juice did, and blocked all seven enzymes tested by more than 70% at 5% juice. No study showing an effect on medicines in people was found. A pharmacist can check your medicines. Laboratory research 11 24
- Allergy to star fruit has been reported. Case reports describe anaphylaxis after a first exposure in one person and oral allergy syndrome in another. Only the titles could be read. How common star fruit allergy is was not found. Case report 21 15
Side effects 3
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Persistent hiccups, vomiting, confusion, numb or weak limbs, seizures and coma in people with kidney disease (neurotoxicity) Reports are of written-up cases. Seizures were linked to the highest death rates (75% in one review of 53 patients). | In 32 patients with kidney failure: hiccups 93.75%, vomiting 68.7%, confusion 65.6%, seizures 21.8% | severe to fatal Patients treated promptly with hemodialysis recovered without lasting problems in one series; some died | Case report 14 4 19 20 10 6 16 |
| Sudden kidney injury from oxalate crystals after large amounts of juice, many fruits or star fruit liquor Includes people with normal kidney function before. A year-long heavy habit was reported once. | Not established | moderate to severe Most recovered in 2 weeks to 4 weeks; one report progressed to chronic kidney disease | Case report 5 1 9 17 |
| Allergic reactions, including anaphylaxis in one case and oral allergy syndrome in another Titles only; no abstract text. | Not established | severe (one case) Not stated (title only) | Case report 21 15 |
Liver
No liver injury from eating star fruit was found in the sources read. LiverTox was not checked. Test-tube work shows the juice blocks liver enzymes that process medicines (see interactions). 11 24
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Star Fruit supports liver health.
Medicines and supplements 3
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Medicines processed by the liver enzymes CYP3A and other CYP enzymes prescription | In human liver tissue in a test tube, star fruit juice strongly blocked CYP3A (0.1% activity left at 5% juice, versus 14.7% for grapefruit) and blocked seven CYP enzymes by more than 70% at 5% juice. | Not shown in people. No study of an effect on any medicine in people was found. | Laboratory research Very low certainty 11 24 | If you take medicines, ask a pharmacist before eating star fruit or drinking its juice regularly. |
| Dialysis and kidney disease treatment condition | Healthy kidneys clear the toxin; diseased kidneys do not. Dialysis has been used to treat poisoning (hemodialysis helped; peritoneal dialysis did not in one series). | Poisoning can be fatal in people with kidney failure. | Case report Low certainty 29 14 6 | People with kidney disease should avoid star fruit. |
| Potassium-limiting diets in kidney disease diet | High potassium (hyperkalaemia) was among the signs reported in a series of dialysis patients after eating star fruit. USDA lists 133 mg potassium per 100 g. | Reported in the series; the abstract does not say whether the fruit itself raised it. | Case report Very low certainty 20 32 | Ask a dietitian about fruit choices if you are on a potassium-limited diet. |
Who should check first 4
| Situation | Advice | Evidence |
|---|---|---|
| Chronic kidney disease, kidney failure, dialysis, or told that your kidneys are weak | Avoid star fruit and its juice. Talk to your kidney team or dietitian about other fruit. | Case report 29 4 14 19 20 10 6 16 |
| Dehydration, or drinking sour juice on an empty stomach | Case reports and a review list these as added risk factors for kidney injury. | Case report 5 12 |
| Taking medicines, especially ones with a grapefruit warning | Ask a pharmacist. The CYP data are test-tube results only. | Laboratory research 11 24 |
| A past allergic reaction to star fruit | Avoid it and see an allergist. Call emergency services for trouble breathing or swelling of the face or throat. | Case report 21 15 |
Overdose, product quality and regulators
Summary. Star fruit contains oxalate, which can damage the kidneys, and a nerve toxin called caramboxin, which healthy kidneys can clear. The point at which harm begins is not known.
Animal. A neurotoxic fraction from star fruit blocked GABA binding and caused seizures when injected into the brains of animals.
Human doses studied. No dose trial in people. Case reports describe two whole fruits in a person with kidney disease and large amounts of juice or many fruits in people with and without kidney disease.
High dose or long term signals. A report of chronic kidney disease after 2 to 3 years of regular heavy eating and a second after drinking liquor made with the fruit.
Overdose response. Hemodialysis (early and continuous) was linked to better survival in a review of 126 cases; peritoneal dialysis did not help in one series.
Genotoxicity. Not researched.
Toxic or hazardous parts. The fruit and its juice are reported in the poisonings. Leaf and root toxicity in people was not found. A rat study of leaf toxicity exists but was not read.
Washing produce reduces dirt and germs. Pesticide residues and heavy metals on star fruit were not researched.
Food safety handling. The FDA says to wash produce under running water, avoid soap or produce wash, cut away bruised or damaged areas, and keep cut produce at 40 F (4 C) or below. 25
Oxalate content of juice. A 2001 report says commercial carambola juice is usually pickled and diluted, which lowers oxalate a lot, while pure fresh or lightly diluted pickled juice used as a remedy has high oxalate. 5
| Body | Action | Date |
|---|---|---|
| National Kidney Foundation (US) (United States) | People with kidney disease should avoid starfruit because of a neurotoxin; consult your healthcare provider or dietitian source | |
| FDA (US Food and Drug Administration) (United States) | Produce safety guidance: wash, cut away damaged areas, refrigerate cut produce. It does not mention star fruit. source | |
| NHS (UK) (United Kingdom) | Vitamin C: adults need 40 mg a day; more than 1,000 mg a day of supplements can cause stomach pain and diarrhoea. No star fruit statement. source | 2020-08-03 |
When to get medical help
- After eating star fruit or its juice, in someone with kidney disease: hiccups that will not stop, vomiting, confusion, numb or weak limbs or a seizure. Call emergency services and tell them about the fruit.
- After drinking a lot of sour star fruit juice: severe abdominal or back pain, very little urine, nausea and vomiting.
- Trouble breathing, swelling of the lips, face or throat, or widespread hives after eating star fruit.
Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.
General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.
Frequently asked questions
Is star fruit safe to eat?
Why is star fruit dangerous for kidney patients?
How many people have died from star fruit?
What are the signs of star fruit poisoning?
Can star fruit hurt people with healthy kidneys?
Does star fruit lower blood sugar or help diabetes?
Does star fruit lower cholesterol or blood pressure?
Does star fruit fight cancer?
No. A leaf extract lowered the survival of breast cancer cells in a dish. That is lab work, not evidence that eating the fruit does anything for cancer.
Is star fruit a good source of vitamin C?
Does star fruit interact with medicines?
Is star fruit safe in pregnancy or for children?
We did not find an official source on star fruit in pregnancy, breastfeeding or children. Ask your doctor or midwife.
Explore by health goal
Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-25
- Last substantive update
- 2026-10-25
- How we research
- We started from our existing star fruit summary, re-checked nutrition at USDA FoodData Central, and searched PubMed for human reports, reviews, mechanism and enzyme studies. Only abstracts were read for studies; two allergy reports were read by title only. Items we could not verify are flagged in the research gaps.
- How we rate evidence
- See "How we rate evidence" in the Evidence tab.
- Independence
- No product is promoted on this page. No affiliate links are shown.
Sources 32
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Abeysekera RA, et al.. Star fruit toxicity: a cause of both acute kidney injury and chronic kidney disease: a report of two cases.. BMC Res Notes. 2015. PMID 26680759. DOI 10.1186/s13104-015-1640-8. (abstract)
- Beas-Guzman OF, et al.. Ethanolic Extract of Averrhoa carambola Leaf Has an Anticancer Activity on Triple-Negative Breast Cancer Cells: An In Vitro Study.. Pharmaceutics. 2024. PMID 39861654. DOI 10.3390/pharmaceutics17010002. (abstract)
- Carolino RO, et al.. Convulsant activity and neurochemical alterations induced by a fraction obtained from fruit Averrhoa carambola.. Neurochem Int. 2005. PMID 15843046. DOI 10.1016/j.neuint.2005.02.002. (abstract)
- Chang JM, et al.. Fatal outcome after ingestion of star fruit (Averrhoa carambola) in uremic patients.. Am J Kidney Dis. 2000. PMID 10676715. DOI 10.1016/s0272-6386(00)70325-8. (abstract)
- Chen CL, et al.. Acute oxalate nephropathy after ingestion of star fruit.. Am J Kidney Dis. 2001. PMID 11157385. DOI 10.1053/ajkd.2001.21333. (abstract)
- Chua CB, et al.. Association of renal function and symptoms with mortality in star fruit (Averrhoa carambola) intoxication.. Clin Toxicol (Phila). 2017. PMID 28443386. DOI 10.1080/15563650.2017.1314490. (abstract)
- Flores Flores MA, et al.. Potential of Fruits to Improve Dyslipidemias: A Pilot Review.. Vasc Health Risk Manag. 2025. PMID 40322293. DOI 10.2147/VHRM.S488465. (abstract)
- Garcia-Cairasco N, et al.. Elucidating the neurotoxicity of the star fruit.. Angew Chem Int Ed Engl. 2013. PMID 24281890. DOI 10.1002/anie.201305382. (abstract)
- Herath N, et al.. Acute Kidney Injury Following Star Fruit Ingestion: A Case Series.. Wilderness Environ Med. 2021. PMID 33518496. DOI 10.1016/j.wem.2020.11.003. (abstract)
- Herbland A, et al.. Star fruit poisoning is potentially life-threatening in patients with moderate chronic renal failure.. Intensive Care Med. 2009. PMID 19360394. DOI 10.1007/s00134-009-1490-8. (abstract)
- Hidaka M, et al.. Potent inhibition by star fruit of human cytochrome P450 3A (CYP3A) activity.. Drug Metab Dispos. 2004. PMID 15155547. DOI 10.1124/dmd.32.6.581. (abstract)
- Lakmal K, et al.. Nutritional and medicinal properties of Star fruit (Averrhoa carambola): A review.. Food Sci Nutr. 2021. PMID 33747490. DOI 10.1002/fsn3.2135. (abstract)
- Luan F, et al.. Traditional Uses, Phytochemical Constituents and Pharmacological Properties of Averrhoa carambola L.: A Review.. Front Pharmacol. 2021. PMID 34475822. DOI 10.3389/fphar.2021.699899. (abstract)
- Neto MM, et al.. Intoxication by star fruit (Averrhoa carambola) in 32 uraemic patients: treatment and outcome.. Nephrol Dial Transplant. 2003. PMID 12480969. DOI 10.1093/ndt/18.1.120. (abstract)
- Numata T, et al.. A case of oral allergy syndrome due to star fruit sensitized from atopic hands.. Allergol Int. 2015. PMID 26433542. DOI 10.1016/j.alit.2015.06.011. (title-only)
- Raciti C, et al.. Death associated with ingestion of starfruit (Averrhoa carambola) in a patient with chronic kidney disease.. Am J Emerg Med. 2023. PMID 37394384. DOI 10.1016/j.ajem.2023.06.043. (abstract)
- Shan S, et al.. Case Report: A case of acute kidney injury due to star fruit-infused liquor.. Front Med (Lausanne). 2026. PMID 42712500. DOI 10.3389/fmed.2026.1932834. (abstract)
- Shui G, Leong LP.. Analysis of polyphenolic antioxidants in star fruit using liquid chromatography and mass spectrometry.. J Chromatogr A. 2004. PMID 14753772. DOI 10.1016/j.chroma.2003.09.055. (abstract)
- Tsai MH, et al.. Status epilepticus induced by star fruit intoxication in patients with chronic renal disease.. Seizure. 2005. PMID 16169255. DOI 10.1016/j.seizure.2005.08.004. (abstract)
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- . NHS: Vitamin C. . . (full-text)
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